When wireless communication is performed between a plurality of wireless communication devices installed in different vehicles, in order to avoid the occurrence of interference with other wireless communications, switching control of frequency channel is performed. In the switching control, channel scanning is performed to detect frequency channels currently used by surrounding wireless communication devices, and a frequency channel used for wireless communication is changed to an unused channel.
A method of appropriately changing a frequency channel in wireless communication in a vehicle according to communication conditions is disclosed in, for example, the following Patent Document 1.
In the disclosed method, quality of image data is measured as a characteristic of a currently used frequency channel, and the measurement period is changed according to the moving speed of a vehicle. Specifically, the change is made such that the longer measurement period is set as the moving speed of the vehicle is getting higher.
By changing the measurement period according to the moving speed of the vehicle, measurement accuracy can be improved. It enables the wireless communication to perform frequency channel switching depending on communication conditions.